1. Field of the Invention
The present invention relates to a storage medium having stored thereon an image processing program and an image processing apparatus. More particularly, the present invention relates to a storage medium having stored thereon an image processing program and an image processing apparatus which are capable of drawing an image of a curved surface (e.g., a curved surface indicative of a landform) as viewed from a virtual camera situated in a virtual three-dimensional space, an undulation of the curved surface being defined by a distance from a virtual plane surface arranged in the virtual three-dimensional space.
2. Description of the Background Art
Conventionally, when an image of a three-dimensional object as viewed from a virtual camera, the image being arranged in a virtual three-dimensional space, is to be drawn, the three-dimensional object is simply represented by image information composed of polygons, whereby the three-dimensional object is situated in the virtual three-dimensional space and the image is drawn therein. However, since the three-dimensional object is represented with a fixed degree of accuracy (that is, since the three-dimensional object is divided into polygons of a common size so as to configure a polygon model thereof), a problem is posed in that a huge amount of data needs to be processed.
In order to solve the problem, various methods, apparatus, and the like have been proposed. For example, a three-dimensional game apparatus is disclosed in which a plurality of types of division map information, which represents the three-dimensional object and which have different numbers of divisions, respectively, is stored in division map information storage means. A distance between the virtual camera and the three-dimensional object is calculated, and the division map information which has a smaller number of divisions is read when the distance becomes further (e.g., see Japanese Patent No. 3227158).
However, in the above-described three-dimensional game apparatus, since the plurality types of division map information (i.e., polygon information), which respectively have different numbers of divisions, needs to be stored in the storage means, the storage means such as a memory needs to have a large amount of capacity. Further, in the above-described three-dimensional game apparatus, if there are a greater number of types of the division map information which respectively have different numbers of divisions, an appropriate division map can be selected in accordance with the distance between the virtual camera and the three-dimensional object (i.e., a division map which is divided into a given number of divisions which are essential to secure a quality of the drawing, can be selected). However, the storage means such as the memory needs to have a further larger amount of capacity.